In electrical connectors particularly for use in hospitals and in other areas where flammable gases or vapors are encountered, it is necessary to provide a grounded receptical device for electrically operated equipment, to prevent voltage leakages which could cause sparks, thereby resulting in explosions of the hazardous and flammable gases and vapors surrounding such electrical connections. Additionally, precision electronic instruments utilized in hospitals and other type laboratories must be protected from voltage leakages which may be critical to the efficiency and accuracy of the instrument for instrument readings. Also, the prevention of shock producing voltage leakage to personnel attending equipment must be considered.
In the past, most devices in use for accomplishing the grounding of electrical devices, in hospitals and other areas containing complicated electronic equipment as well as hazardous vapors and gases, have included the use of a standard receptacle adapted to receive a three-way plug wherein one of the conductors is a grounding blade. However, these devices do not provide a fail-safe device wherein the electrical connections can be made only after the ground contact has been engaged with the ground terminal. Consequently, such devices have failed to provide a tamper-proof fail-safe device which provides that before the electrical contacts between the plug and receptacle can be made the ground connection must be completed.